Luang Lake, Thai Thale Luang, also called Thale Sap, coastal lake or lagoon (thale), southern Thailand, on the east coast of the Malay Peninsula. The lake, 50 miles (80 km) long and up to 15 miles (24 km) wide, is dotted with islands. It is a fertile fishing ground and is connected to the Gulf of Thailand at Songkhla town on its southern shore.